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Weiqi Luo - One of the best experts on this subject based on the ideXlab platform.
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Efficacy of the entomopathogenic nematode, Steinernema feltiae, against sweetpotato whitefly Bemisia tabaci (Homoptera: Aleyrodidae) under laboratory and glasshouse conditions.
Bulletin of entomological research, 2007Co-Authors: Andrew G. S. Cuthbertson, Keith F. A. Walters, Phil Northing, Weiqi LuoAbstract:The potential of using the entomopathogenic nematode Steinernema feltiae to control the sweetpotato whitefly Bemisia tabaci (Gennadius) has been established in previous laboratory studies. However, laboratory studies can overestimate the level of control achieved by biocontrol agents in the glasshouse. Glasshouse trials are therefore required to confirm laboratory results before full-scale commercial development is considered. Under both controlled laboratory and glasshouse conditions high mortality of second instar B. tabaci (>90% and >80%, respectively) was recorded after application of S. feltiae . The efficacy of the biocontrol agent at various application rates was also investigated, where halving the rate of S. feltiae application caused no significant reduction in B. tabaci mortality on tomato foliage. Steinernema feltiae has shown much potential for incorporation into integrated pest management strategies for the control of B. tabaci .
Alper I. Susurluk - One of the best experts on this subject based on the ideXlab platform.
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Seasonal and vertical distribution of the entomopathogenic nematodes Heterorhabditis bacteriophora (TUR-H2) and Steinernema feltiae (TUR-S3) in turf and fallow areas
Nematology, 2009Co-Authors: Alper I. SusurlukAbstract:To determine the seasonal movement of the dauer juvenile (DJ) stage of entomopathogenic nematodes, DJ of Heterorhabditis bacteriophora (TUR-H2) and Steinernema feltiae (TUR-S3) were applied to field plots (turf and fallow) and their vertical distribution in soil was monitored for 8 months (October to June) in Turkey. Most S. feltiae remained near the soil surface (0-15 cm deep) in both kinds of plots and throughout the study. By contrast, H. bacteriophora moved to 40 cm depth in fallow plots during winter months but remained mostly near the soil surface (0-15 cm deep) in turf plots throughout the study.
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Potential of the entomopathogenic nematodes Steinernema feltiae, S. weiseri and Heterorhabditis bacteriophora for the biological control of the sugar beet weevil Bothynoderes punctiventris (Coleoptera: Curculionidae)
Journal of Pest Science, 2008Co-Authors: Alper I. SusurlukAbstract:The sugar beet weevil, Bothynoderes punctiventris Germ. (Coleoptera: Curculionidae), is one of the most damaging pests of sugar beets in Turkey and has been traditionally controlled by application of large amounts of insecticides. The current study used laboratory microcosms to evaluate the possibility of using entomopathogenic nematodes as an alternative control method. The nematodes Steinernema feltiae (strain TUR-S3), Steinernema weiseri (BEY) and Heterorhabditis bacteriophora (TUR-H2) had previously been isolated from Turkey. Nematode-induced mortality generally increased as soil temperature increased from 15 to 25°C but decreased when larvae were located deeper in soil. Heterorhabditis bacteriophora caused the highest larval mortality at 25°C at all depths (5–20 cm). Steinernema feltiae and S. weiseri were more effective than H. bacteriophora at 15°C at all depths. Increasing the application rate of infective nematode dauer juveniles (DJs) affected the number of DJs that penetrated each insect larva and the number of DJs produced per insect. The highest production of DJs per larva occurred at application rates of 50 DJs/larva for S. feltiae and S. weiseri and 100 DJs/larva for H. bacteriophora. Reproduction decreased again at higher application rates. Heterorhabditis bacteriophora had the highest reproductive capability. The results indicate that S. feltiae and S. weiseri might be more effective against this pest early in the growing season when soil temperature is low and that H. bacteriophora might be more effective later in the season when temperature increases.
Andrew G. S. Cuthbertson - One of the best experts on this subject based on the ideXlab platform.
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Efficacy of the entomopathogenic nematode, Steinernema feltiae, against sweetpotato whitefly Bemisia tabaci (Homoptera: Aleyrodidae) under laboratory and glasshouse conditions.
Bulletin of entomological research, 2007Co-Authors: Andrew G. S. Cuthbertson, Keith F. A. Walters, Phil Northing, Weiqi LuoAbstract:The potential of using the entomopathogenic nematode Steinernema feltiae to control the sweetpotato whitefly Bemisia tabaci (Gennadius) has been established in previous laboratory studies. However, laboratory studies can overestimate the level of control achieved by biocontrol agents in the glasshouse. Glasshouse trials are therefore required to confirm laboratory results before full-scale commercial development is considered. Under both controlled laboratory and glasshouse conditions high mortality of second instar B. tabaci (>90% and >80%, respectively) was recorded after application of S. feltiae . The efficacy of the biocontrol agent at various application rates was also investigated, where halving the rate of S. feltiae application caused no significant reduction in B. tabaci mortality on tomato foliage. Steinernema feltiae has shown much potential for incorporation into integrated pest management strategies for the control of B. tabaci .
Carmen Gutiérrez - One of the best experts on this subject based on the ideXlab platform.
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Steinernema feltiae Intraspecific Variability: Infection Dynamics and Sex-Ratio
Journal of nematology, 2014Co-Authors: Raquel Campos-herrera, Carmen GutiérrezAbstract:Entomopathogenic nematodes (EPNs) from the Heterorhabditidae and Steinernematidae families are well-known biocontrol agents against numerous insect pests. The infective juveniles (IJs) are naturally occurring in the soil and their success in locating and penetrating the host will be affected by extrinsic/intrinsic factors that modulate their foraging behavior. Characterizing key traits in the infection dynamics of EPNs is critical for establishing differentiating species abilities to complete their life cycles and hence, their long-term persistence, in different habitats. We hypothesized that phenotypic variation in traits related to infection dynamics might occur in populations belonging to the same species. To assess these intraspecific differences, we evaluated the infection dynamics of 14 populations of Steinernema feltiae in two experiments measuring penetration and migration in sand column. Intraspecific variability was observed in the percentage larval mortality, time to kill the insect, penetration rate, and sex-ratio in both experiments (P < 0.01). Larval mortality and nematode penetration percentage were lower in migration experiments than in penetration ones in most of the cases. The sex-ratio was significantly biased toward female-development dominance (P < 0.05). When the populations were grouped by habitat of recovery (natural areas, crop edge, and agricultural groves), nematodes isolated in natural areas exhibited less larval mortality and penetration rates than those from some types of agricultural associated soils, suggesting a possible effect of the habitat on the phenotypic plasticity. This study reinforces the importance of considering intraspecific variability when general biological and ecological questions are addressed using EPNs.
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a laboratory study on the activity of Steinernema feltiae rhabditida Steinernematidae rioja strain against horticultural insect pests
Journal of Pest Science, 2009Co-Authors: Raquel Camposherrera, Carmen GutiérrezAbstract:The potential of the entomopathogenic nematode Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) Rioja strain was assessed under laboratory conditions. Last instar larvae of Leptinotarsa decemlineata Say (Coleptera: Chrysomelidae), Spodoptera littoralis Boisdouval (Lepidoptera: Noctuidae) and Trichoplusia ni Hubner (Lepidoptera: Noctuidae) were exposed to infective juveniles (IJs) under laboratory conditions. Larval mortality, days to larval death, infection cycle length, and reproductive potential were recorded. Efficacy was assessed performing dose–response experiments. The results indicate that control of L. decemlineata with S. feltiae Rioja strain is not economically profitable (LC50 = 99.61 IJs/cm2), whereas results obtained for T. ni (LC50 = 0.27 IJs/cm2) are promising. Due to the life cycle of this insect, the efficacy needs to be investigated in foliar application studies. The effects on S. littoralis (LC50 = 0.69 IJs/cm2) was considered the most suitable for development of the Rioja strain as a biocontrol agent for soil application.
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Comparative study of the effect of selected agrochemical products on Steinernema feltiae (Rhabditida: Steinernematidae)
Biocontrol Science and Technology, 2008Co-Authors: Carmen Gutiérrez, Raquel Campos-herrera, Jesús JiménezAbstract:Abstract The effect of three neurotoxic insecticides, three photosynthetic inhibitor herbicides and three enzymatic inhibitor herbicides on infective juveniles (IJs) of Steinernema feltiae Rioja (native) and ENTONEM® (commercial) strains were evaluated after a 48-h exposure at field tank concentrations and overnight treatment in mQ-water, using Spodoptera littoralis as target. Nematode survival was not affected by acetyl-cholinesterase inhibitors chlorpyrifos and pirimicarb, although chlorpyrifos seriously reduced their virulence. Both nematode strains showed differential sensitivity to cypermethrin, which affects the sodium channels of the nerve membrane, with the ENTONEM® strain being more tolerant than Rioja strain. However, these chemicals showed a strong sublethal effect on the nematode reproductive potential, limiting seriously their possible recycling in the field. Herbicides showed differential toxic effects on nematode survival. The commercial strain was tolerant to enzymatic inhibitor herbicides...
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Phoresy of the entomopathogenic nematode Steinernema feltiae by the earthworm Eisenia fetida
Journal of Invertebrate Pathology, 2006Co-Authors: Raquel Campos-herrera, D. Trigo, Carmen GutiérrezAbstract:Abstract The free-living stage of entomopathogenic nematodes occurs in soil, and is an environmental-friendly alternative for biological control. However, their dispersal capability is limited. Earthworms improve soil characteristics, changing soil structure and influencing many edaphic organisms. Thus, earthworms could be used as vectors to introduce/disperse beneficial organisms. Nevertheless this interaction has not been studied in detail. This study presents the infectivity results of Steinernema feltiae after passing through the Eisenia fetida gut. Although entomopathogenic nematodes have no deleterious effects on earthworms, their passage through E. fetida gut seriously affected their mobility and virulence.
Randy Gaugler - One of the best experts on this subject based on the ideXlab platform.
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Effect of Steinernema feltiae-Xenorhabdus bovienii insect pathogen complex on Meloidogyne javanica
Nematology, 2004Co-Authors: Declan J. Fallon, Harry K. Kaya, Randy Gaugler, Brent S. SipesAbstract:Isolates of Steinernema feltiae MG-14 from Hawaii and SN from France, and the symbiont Xenorhabdus bovienii from each nematode isolate, were tested for their glasshouse efficacy against the root-knot nematode, Meloidogyne javanica, on several vegetable plants. Steinernema feltiae application for 3-5 consecutive days at rates of 1000 or 10 000 infective juveniles (IJ) did not affect M. javanica root penetration and development in glasshouse pot experiments. IJ were recovered from the cortical tissue of tomatoes, soybeans, snow peas and cow peas. Xenorhabdus bovienii applied at 1010 colony-forming units (CFU) ml–1 reduced root-knot nematode penetration in cow peas but was ineffective in tomato or snow pea. Xenorhabdus bovienii metabolites had no effect on M. javanica root penetration and egg production in soybean. Soybean plant growth was unaffected by nematode and bacterial treatment; biomass was lower in M. javanica-infected soybean, irrespective of treatment, than in non-infected soybean, but the differences between the treatments were non-significant. Accordingly, the Steinernema feltiae-Xenorhabdus bovienii complex did not meet the objective for the suppression of M. javanica root penetration and development.
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enhanced cold tolerance of the entomopathogenic nematode Steinernema feltiae through genetic selection
Annals of Applied Biology, 1996Co-Authors: Parwinder S. Grewal, Randy Gaugler, Yi WangAbstract:Summary. Cold sensitivity of entomopathogenic nematodes severely restricts their biological control potential in some environments. We selected the SN strain of Steinernema feltiae together with its bacterial symbiont, Xenorhabdus bovenii, for improved cold tolerance by repeated passage through the wax moth Galleria mellonella larvae at 15°C. Nematode virulence (total insect mortality and speed of kill) and establishment (initiation of nematode development following penetration) were evaluated after six (= 12–24 generations) and 12 passages (= 24–36 generations). Cold selection enhanced nematode virulence at the cooler temperatures. Virulence measured as total insect-mortality at 8°C improved by 5.3- and 6.6-fold after six and 12 passages, respectively. Only small improvements (1.2–1.5-fold) were observed in speed of kill. Nematode establishment improved at all temperatures after 12 passages; the highest increase of 9-fold was observed at 8°C. Our results lend support to the hypotheses that functional traits along a continuously distributed environmental variable are genetically correlated and that the area under the fitness function is not always constant. Trade-offs in percentage mortality and speed of kill by the selected nematodes were observed at the warmer extreme after six passages of selection only. The implications of rapid changes in thermal sensitivity for economic mass-production of nematodes are discussed.